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The European Commission has funded within its 6th Framework Programme a three-year project (2005–2007) called CONRAD, COordinated Network for RAdiation Dosimetry. The organizational framework for this project was provided by the European radiation Dosimetry Group EURADOS. Work Package 6 of CONRAD dealt with “complex mixed radiation fields at workplaces” and in this context it organised a benchmark exercise, which included both measurements and calculations, in a stray radiation field at a high-energy particle accelerator at GSI, Germany. The aim was to intercompare the response of several types of active detectors and passive dosemeters in a well-characterised workplace field. The Monte Carlo simulations of the radiation field and the experimental determination of the neutron spectra with various Bonner Sphere Spectrometers are discussed in Rollet et al. (2008) and in Wiegel et al. (2008). This paper focuses on the intercomparison of the response of the dosemeters in terms of ambient dose equivalent. The paper describes in detail the detectors employed in the experiment, followed by a discussion of the results. A comparison is also made with the H*(10) values predicted by the Monte Carlo simulations and those measured by the BSS systems.

The neutron capture cross section 209Bi(n, γ) 210mBi was measured by means of accelerator mass spectrometry (AMS). An absolute measuring procedure based on calibrated ion beam attenuators was applied to overcome the lack of standard samples. Experimental aspects of absolute AMS analyses are described. The capture cross section of 209Bi is important in the construction of accelerator-driven transmutation (ADT) devices that are based on the Pb–Bi eutectic complex as the spallation target to produce very intense neutron fluxes.

AMS with tritium is a method able to detect even very small nuclear releases. It was applied in this work to monitor the tritium concentration at nuclear power plants (CANDU-type) and at nuclear fuel reprocessing plants and to diagnose fusion experiments. Two different depth profiling measuring procedures are presented. AMS measurements of the tritium, created in D–D fusion reactions offered detailed information about the spatial distribution of Triton fluxes to the vessel wall of a Tokamak, about the plasma confinement and about the interaction of the heating neutral deuterium beam with the confined and rotating plasma.

A new time-of-flight set-up for accelerator mass spectrometry with 129I was installed at the Maier-Leibnitz laboratory in Garching (Germany). The detector system consists of a TOF-system and an ionization chamber. A TOF resolution of 440 ps is obtained, the energy resolution is about 2%. The sensitivity of the complete system is 10−14 for the ratio of 129I/127I. The measurements of rain water samples from the time period between July 2003 and October 2004 showed a decrease of 129I concentration, of 129I deposition flux and of 129I/127I isotopic ratio compared to previous measurements of rain water in Southern Germany from 1988, 1989 and 1995. This decrease can be explained by a substantial drop in gaseous 129I emissions from the French reprocessing facilities.

Wet and, to a lesser extent, dry deposition of atmospheric (129)I are known to represent the dominating processes responsible for (129)I in continental environmental samples that are remote from (129)I sources and not directly influenced by any liquid (129)I release of nuclear installations. Up to now, however, little is known about the major emitters and the related global deposition pattern of (129)I. In this work an overview over major sources of (129)I is given, and hitherto unknown time-dependent releases from these were estimated. Total gaseous (129)I releases from the US and former Soviet reprocessing facilities Hanford, Savannah River, Mayak, Seversk and Zheleznogorsk were found to have been 0.53, 0.27, 1.05, 0.23 and 0.14TBq, respectively. These facilities were thus identified as major airborne (129)I emitters. The global deposition pattern due to the (129)I released, depending on geographic latitude and longitude, and on time was studied using a box model describing the global atmospheric transport and deposition of (129)I. The model predictions are compared to (129)I concentrations measured by means of Accelerator Mass Spectrometry (AMS) in water samples that were collected from various lakes in Asia, Africa, America and New Zealand, and to published values. As a result, both pattern and temporal evolution of (129)I deposition values measured in and calculated for different types of environmental samples are, in general, in good agreement. This supports our estimate on atmospheric (129)I releases and the considered substantial transport and deposition mechanisms in our model calculations.

Estimates of (129)I depositions from (129)I releases of reprocessing plants are so far based on measurements of soil and rain water samples. Because (129)I concentrations in these samples show a highly temporal and spatial variability, the (129)I deposition values deduced from single measurements cannot be seen as representative for a larger area. Here it is proposed to use lake water as an archive for former (129)I depositions, to overcome these limitations. If the limnological parameters of any lake are known, the local (129)I deposition flux can be deduced which is temporally averaged over the flushing time, and spatially averaged over the catchment area of the lake. Samples were collected from various European lakes and from Lake Baikal (Russia). The (129)I concentration in these samples was measured by means of accelerator mass spectrometry, and values between 0.3 and 8.1x10(8) at/l were obtained. Deduced (129)I deposition fluxes averaged over the flushing times of the lakes range from 0.3 to 9.3x10(12) at/m(2) y. The (129)I deposition fluence measured for Lake Baikal is attributed predominantly to releases from the former Soviet reprocessing facilities Chelyabinsk, Tomsk and Krasnoyarsk, while the (129)I deposition fluxes deduced for all other lakes are attributed to releases from the European reprocessing activities at Sellafield, Marcoule and La Hague.